1. Field
This invention is directed generally to a hoisting device and particularly to a device for hoisting cables overhead.
2. State of the Art
Prior art devices such as those shown in U.S. Pat. Nos. 898,010; 2,130,464; 2,553,779 and 2,951,596 are representative of the devices and techniques heretofore employed in placing cables on an overhead structure. In each instance, the devices employed are specifically designed for lifting cables; however, they are generally incapable of positioning the lifted cable at a particular point of placement on the overhead structure.
Further, the devices shown in the above patents have limited capabilities of redistributing the forces encountered during the lifting process, particularly when the angle of the jib or boom is altered. As a result, the devices have limited application in raising or lifting heavy loads. In those instances where the devices are designed to handle heavy loads, they are from a structural standpoint, very large and cumbersome and as a result cannot be readily transported and used in areas where vehicular movement is restricted.
To overcome the above shortcomings, it is a primary object of this invention to provide a hoisting device which is portable and which is capable of being used in areas which would normally be inaccessible. Another object of this invention is to provide a hoisting device which is structurally sound and operationally safe. Still another object of this invention is to provide a hoisting device which is capable of lifting up to forty times its own weight. Another object of this invention is to provide a hoisting device which can lift and move cables in both a vertical and a horizontal plane. A final object of this invention is to provide a device capable of transferring lifting forces to the base of the jib over a broad range of angular positions.